1 /* vi: set sw=4 ts=4: */
5 * Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
6 * Copyright (C) 2005 by Rob Landley <rob@landley.net>
8 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
11 #include <linux/version.h>
13 #if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,0)
15 /* For 2.6, use the cleaned up header to get the 64 bit API. */
16 // Commented out per Rob's request
17 //# include "fix_u32.h" /* some old toolchains need __u64 for linux/loop.h */
18 # include <linux/loop.h>
19 typedef struct loop_info64 bb_loop_info;
20 # define BB_LOOP_SET_STATUS LOOP_SET_STATUS64
21 # define BB_LOOP_GET_STATUS LOOP_GET_STATUS64
25 /* For 2.4 and earlier, use the 32 bit API (and don't trust the headers) */
26 /* Stuff stolen from linux/loop.h for 2.4 and earlier kernels */
27 # include <linux/posix_types.h>
28 # define LO_NAME_SIZE 64
29 # define LO_KEY_SIZE 32
30 # define LOOP_SET_FD 0x4C00
31 # define LOOP_CLR_FD 0x4C01
32 # define BB_LOOP_SET_STATUS 0x4C02
33 # define BB_LOOP_GET_STATUS 0x4C03
36 __kernel_dev_t lo_device;
37 unsigned long lo_inode;
38 __kernel_dev_t lo_rdevice;
41 int lo_encrypt_key_size;
43 char lo_file_name[LO_NAME_SIZE];
44 unsigned char lo_encrypt_key[LO_KEY_SIZE];
45 unsigned long lo_init[2];
50 char* FAST_FUNC query_loop(const char *device)
53 bb_loop_info loopinfo;
56 fd = open(device, O_RDONLY);
58 if (ioctl(fd, BB_LOOP_GET_STATUS, &loopinfo) == 0) {
59 dev = xasprintf("%"OFF_FMT"u %s", (off_t) loopinfo.lo_offset,
60 (char *)loopinfo.lo_file_name);
68 int FAST_FUNC del_loop(const char *device)
72 fd = open(device, O_RDONLY);
75 rc = ioctl(fd, LOOP_CLR_FD, 0);
81 /* Returns opened fd to the loop device, <0 on error.
82 * *device is loop device to use, or if *device==NULL finds a loop device to
83 * mount it on and sets *device to a strdup of that loop device name. This
84 * search will re-use an existing loop device already bound to that
85 * file/offset if it finds one.
87 int FAST_FUNC set_loop(char **device, const char *file, unsigned long long offset, unsigned flags)
89 char dev[LOOP_NAMESIZE];
91 bb_loop_info loopinfo;
93 int i, dfd, ffd, mode, rc;
97 /* Open the file. Barf if this doesn't work. */
98 mode = (flags & BB_LO_FLAGS_READ_ONLY) ? O_RDONLY : O_RDWR;
100 ffd = open(file, mode);
102 if (mode != O_RDONLY) {
109 /* Find a loop device. */
110 try = *device ? *device : dev;
111 /* 1048575 (0xfffff) is a max possible minor number in Linux circa 2010 */
112 for (i = 0; rc && i < 1048576; i++) {
113 sprintf(dev, LOOP_FORMAT, i);
115 IF_FEATURE_MOUNT_LOOP_CREATE(errno = 0;)
116 if (stat(try, &statbuf) != 0 || !S_ISBLK(statbuf.st_mode)) {
117 if (ENABLE_FEATURE_MOUNT_LOOP_CREATE
121 /* Node doesn't exist, try to create it. */
122 if (mknod(dev, S_IFBLK|0644, makedev(7, i)) == 0)
125 /* Ran out of block devices, return failure. */
130 /* Open the sucker and check its loopiness. */
131 dfd = open(try, mode);
132 if (dfd < 0 && errno == EROFS) {
134 dfd = open(try, mode);
137 if (errno == ENXIO) {
138 /* Happens if loop module is not loaded */
145 rc = ioctl(dfd, BB_LOOP_GET_STATUS, &loopinfo);
147 /* If device is free, claim it. */
148 if (rc && errno == ENXIO) {
149 /* Associate free loop device with file. */
150 if (ioctl(dfd, LOOP_SET_FD, ffd) == 0) {
151 memset(&loopinfo, 0, sizeof(loopinfo));
152 safe_strncpy((char *)loopinfo.lo_file_name, file, LO_NAME_SIZE);
153 loopinfo.lo_offset = offset;
155 * Used by mount to set LO_FLAGS_AUTOCLEAR.
156 * LO_FLAGS_READ_ONLY is not set because RO is controlled by open type of the file.
157 * Note that closing LO_FLAGS_AUTOCLEARed dfd before mount
158 * is wrong (would free the loop device!)
160 loopinfo.lo_flags = (flags & ~BB_LO_FLAGS_READ_ONLY);
161 rc = ioctl(dfd, BB_LOOP_SET_STATUS, &loopinfo);
162 if (rc != 0 && (loopinfo.lo_flags & BB_LO_FLAGS_AUTOCLEAR)) {
163 /* Old kernel, does not support LO_FLAGS_AUTOCLEAR? */
164 /* (this code path is not tested) */
165 loopinfo.lo_flags -= BB_LO_FLAGS_AUTOCLEAR;
166 rc = ioctl(dfd, BB_LOOP_SET_STATUS, &loopinfo);
169 ioctl(dfd, LOOP_CLR_FD, 0);
184 *device = xstrdup(dev);